NF-κB Signaling is Required for X-Chromosome Inactivation Maintenance Following T cell Activation

X Chromosome Inactivation (XCI) is a female-specific process which balances X-linked gene dosage between sexes. Unstimulated T cells lack cytological enrichment of Xist RNA and heterochromatic modifications on the inactive X chromosome (Xi), and these modifications become enriched at the Xi after cell stimulation. Here, we examined allele-specific gene expression and the epigenomic profiles of the Xi following T cell stimulation. We found that the Xi in unstimulated T cells is largely dosage compensated and is enriched with the repressive H3K27me3 modification, but not the H2AK119-ubiquitin (Ub) mark, even at promoters of XCI escape genes. Upon CD3/CD28-mediated T cell stimulation, the Xi accumulates H2AK119-Ub and H3K27me3 across the Xi. Next, we examined the T cell signaling pathways responsible for Xist RNA localization to the Xi and found that T cell receptor (TCR) engagement, specifically NF-κB signaling downstream of TCR, is required. Disruption of NF-κB signaling, using inhibitors or genetic deletions, in mice and patients with immunodeficiencies prevents Xist/XIST RNA accumulation at the Xi and alters expression of some X-linked genes. Our findings reveal a novel connection between NF-κB signaling pathways which impact XCI maintenance in female T cells.

Optimized x-ray emission from 10 ns long germanium x-ray sources at the National Ignition Facility

This study investigates methods to optimize quasi-monochromatic, ∼10 ns long x-ray sources (XRS) for time-resolved x-ray diffraction measurements of phase transitions during dynamic laser compression measurements at the National Ignition Facility (NIF). To support this, we produce continuous and pulsed XRS by irradiating a Ge foil with NIF lasers to achieve an intensity of 2 × 10¹⁵ W/cm², optimizing the laser-to-x-ray conversion efficiency. Our x-ray source is dominated by Ge He-α line emission. We discuss methods to optimize the source to maintain a uniform XRS for ∼10 ns, mitigating cold plasma and higher energy x-ray emission lines.

CEMDA

People use smartphones to do many tasks: view email attachments, read social media posts, create and edit photographs, and forward files. The user's perspective on actions performed when creating, viewing, and modifying files (her mental model ) reflects the visible clicks and swipes performed. At the file system and OS, however, such actions are less clear. A single click can lead to a flurry of hundreds of file system reads and writes, system calls, and communication steps. While individual apps can use analytics to record in-app user actions, common patterns such as download-read-forward cross app boundaries and become difficult to discover. That lack leads to inefficiencies in on-device file management and backup.

To better enable apps and devices to discover the user's mental model, we present CEMDA, an Android app that automatically detects the user's mental model by applying the theories of file lifecycle events and complex events. CEMDA detects over 10 high level user stories in 4 categories of user actions (create, access, share, modify) while operating completely in user space and without OS modification. CEMDA successfully detects user actions in cross-app actions across popular messaging and productivity apps (e.g., WhatsApp, Adobe Reader) with 75%-100% success while consuming minimal battery and memory.

DANTE as a primary temperature diagnostic for the NIF iron opacity campaign

The Opacity Platform on the National Ignition Facility (NIF) has been developed to measure iron opacities at varying densities and temperatures relevant to the solar interior and to verify recent experimental results obtained at the Sandia Z-machine, that diverge from theory. The first set of NIF experiments collected iron opacity data at ∼150 eV to 160 eV and an electron density of ∼7 × 10²¹ cm^-3, with a goal to study temperatures up to ∼210 eV, with electron densities of up to ∼3 × 10²² cm^-3. Among several techniques used to infer the temperature of the heated Fe sample, the absolutely calibrated DANTE-2 filtered diode array routinely provides measurements of the hohlraum conditions near the sample. However, the DANTE-2 temperatures are consistently low compared to pre-shot LASNEX simulations for a range of laser drive energies. We have re-evaluated the estimated uncertainty in the reported DANTE-2 temperatures and also the error generated by varying channel participation in the data analysis. An uncertainty of ±5% or better can be achieved with appropriate spectral coverage, channel participation, and metrology of the viewing slot.

Spectral sensor error analysis for measuring x-ray radiation drive using the DANTE diagnostic toward inertial confinement fusion experiments

DANTE is a diagnostic used to measure the x-radiation drive produced by heating a high-Z cavity ("hohlraum") with high-powered laser beams. It records the spectrally and temporally resolved radiation flux at x-ray energies between 50 eV and 20 keV. Each sensor configuration on DANTE is composed of filters, mirrors, and x-ray diodes to define 18 different x-ray channels whose output is voltage as a function of time. The absolute flux is then determined from the photometric calibration of the sensor configuration and a spectral reconstructing algorithm. The reconstruction of the spectra vs time from the measured voltages and known response of each channel has presented challenges. We demonstrate a novel approach here for quantifying the error on the determined flux based on the channel sensor configuration and most commonly used reconstruction algorithm. In general, we find that the integrated spectral flux from a hohlraum can robustly be reconstructed (within ∼14%) using a traditional unfold approach with as few as ten channels due to the underlying assumption of a largely Planckian spectral intensity distribution.

Analysis of Calcium Control of Canonical NF-κB Signaling in B Lymphocytes

The central role of calcium (Ca²⁺) signaling in lymphocyte development and acquisition of functional immunity and tolerance is well established. Ca²⁺ signals are initiated upon antigen binding to cognate receptors on lymphocytes that trigger store operated Ca²⁺ entry (SOCE). The underlying mechanism of SOCE in lymphocytes involves TCR and BCR mediated activation of Stromal Interaction Molecule 1 and 2 (STIM1/2) embedded in the ER membrane. Once activated, STIM proteins oligomerize and re-localize to ER domains juxtaposed to the plasma membrane where they activate Orai channels to allow Ca²⁺ to enter the cell across the plasma membrane. Importantly, STIM/Orai-dependent Ca²⁺ signals guide antigen induced lymphocyte development and function principally by regulating the activity of transcription factors.The most widely studied of these transcription factors is the Nuclear Factor of Activated T cells (NFAT). NFAT is expressed ubiquitously and the mechanism by which Ca²⁺ regulates NFAT activation and signaling is well known. By contrast, a mechanistic understanding of how Ca²⁺ signals also shape the activation and specificity of NF-κB to control the expression of pro-inflammatory genes has lagged. Here we discuss the methodology used to investigate Ca²⁺ dependent mechanisms of NF-κB activation in lymphocytes. Our approach focuses on three main areas of signal transduction and signaling: (1) antigen receptor engagement and Ca²⁺ dependent initiation of NF-kB signaling, (2) Ca²⁺ dependent induction of NF-κB heterodimer activation and nuclear localization, and (3) and how Ca²⁺ regulates NF-κB dependent expression of target genes and proteins.

A compact filtered x-ray diode array spectrometer for the National Ignition Facility: SENTINEL

Sentinel is a 16-channel, filtered x-ray diode array spectrometer that has been developed to measure ∼1 keV-20 keV x-ray emission generated by the National Ignition Facility (NIF) laser. Unlike the large, fixed-port versions of this diagnostic that currently exist on the NIF (known as Dante), Sentinel is a Diagnostic Instrument Manipulator compatible such that it can be fielded along the polar or equatorial lines-of-sight-an essential new capability for characterizing the often anisotropic x-ray emission from laser-driven sources. We present the diagnostic design along with preliminary diode calibrations and performance results. The novel, small-form-factor x-ray diode design allows for ≳5×-25× increased channel areal density over that of Dante, simultaneously enabling improved diagnostic robustness and fidelity of spectral reconstructions. While the Sentinel diagnostic is anticipated to improve line-of-sight spectral characterization of x-ray sources for a wide variety of programs on the NIF, the compact and portable design is also attractive to small- and mid-scale facilities with limited diagnostic real estate.

A genetic algorithm approach for reconstructing spectral content from filtered x-ray diode array spectrometers

Filtered diode array spectrometers are routinely employed to infer the temporal evolution of spectral power from x-ray sources, but uniquely extracting spectral content from a finite set of broad, spectrally overlapping channel spectral sensitivities is decidedly nontrivial in these under-determined systems. We present the use of genetic algorithms to reconstruct a probabilistic spectral intensity distribution and compare to the traditional approach most commonly found in the literature. Unlike many of the previously published models, spectral reconstructions from this approach are neither limited by basis functional forms nor do they require a priori spectral knowledge. While the original intent of such measurements was to diagnose the temporal evolution of spectral power from quasi-blackbody radiation sources-where the exact details of spectral content were not thought to be crucial-we demonstrate that this new technique can greatly enhance the utility of the diagnostic by providing more physical spectra and improved robustness to hardware configuration for even strongly non-Planckian distributions.

4-1BB costimulation promotes CAR T cell survival through noncanonical NF-κB signaling

Clinical response to chimeric antigen receptor (CAR) T cell therapy is correlated with CAR T cell persistence, especially for CAR T cells that target CD19⁺ hematologic malignancies. 4-1BB-costimulated CAR (BBζ) T cells exhibit longer persistence after adoptive transfer than do CD28-costimulated CAR (28ζ) T cells. 4-1BB signaling improves T cell persistence even in the context of 28ζ CAR activation, which indicates distinct prosurvival signals mediated by the 4-1BB cytoplasmic domain. To specifically study signal transduction by CARs, we developed a cell-free, ligand-based activation and ex vivo culture system for CD19-specific CAR T cells. We observed greater ex vivo survival and subsequent expansion of BBζ CAR T cells when compared to 28ζ CAR T cells. We showed that only BBζ CARs activated noncanonical nuclear factor κB (ncNF-κB) signaling in T cells basally and that the anti-CD19 BBζ CAR further enhanced ncNF-κB signaling after ligand engagement. Reducing ncNF-κB signaling reduced the expansion and survival of anti-CD19 BBζ T cells and was associated with a substantial increase in the abundance of the most pro-apoptotic isoforms of Bim. Although our findings do not exclude the importance of other signaling differences between BBζ and 28ζ CARs, they demonstrate the necessary and nonredundant role of ncNF-κB signaling in promoting the survival of BBζ CAR T cells, which likely underlies the engraftment persistence observed with this CAR design.

Modeling the one-dimensional imager of neutrons (ODIN) for neutron response functions at the Sandia Z facility

The one-dimensional imager of neutrons (ODIN) at the Sandia Z facility consists of a 10-cm block of tungsten with rolled edges, creating a slit imager with slit widths of either 250, 500, or 750 μm. Designed with a 1-m neutron imaging line of sight, we achieve about 4:1 magnification and 500-μm axial spatial resolution. The baseline inertial confinement fusion concept at Sandia is magnetized liner inertial fusion, which nominally creates a 1-cm line source of neutrons. ODIN was designed to determine the size, shape, and location of the neutron producing region, furthering the understanding of compression quality along the cylindrical axis of magnetized liner implosions. Challenges include discriminating neutrons from hard x-rays and gammas with adequate signal-to-noise in the 2 × 10¹² deuterium-deuterium (DD) neutron yield range, as well as understanding the point spread function of the imager to various imaging detectors (namely, CR-39). Modeling efforts were conducted with MCNP6.1 to determine neutron response functions for varying configurations in a clean DD neutron environment (without x-rays or gammas). Configuration alterations that will be shown include rolled-edge slit orientation and slit width, affecting the resolution and response function. Finally, the experiment to determine CR-39 neutron sensitivity, with and without a high density polyethylene (n, p) converter, an edge spread function, and resolution will be discussed.

Capsule implosions for continuum x-ray backlighting of opacity samples at the National Ignition Facility

Direct drive implosions of plastic capsules have been performed at the National Ignition Facility to provide a broad-spectrum (500-2000 eV) X-ray continuum source for X-ray transmission spectroscopy. The source was developed for the high-temperature plasma opacity experimental platform. Initial experiments using 2.0 mm diameter polyalpha-methyl styrene capsules with ∼20 μm thickness have been performed. X-ray yields of up to ∼1 kJ/sr have been measured using the Dante multichannel diode array. The backlighter source size was measured to be ∼100 μm FWHM, with ∼350 ps pulse duration during the peak emission stage. Results are used to simulate transmission spectra for a hypothetical iron opacity sample at 150 eV, enabling the derivation of photometrics requirements for future opacity experiments.

Understanding reconstructed Dante spectra using high resolution spectroscopy

The Dante is an 18 channel filtered diode array used at the National Ignition Facility (NIF) to measure the spectrally and temporally resolved radiation flux between 50 eV and 20 keV from various targets. The absolute flux is determined from the radiometric calibration of the x-ray diodes, filters, and mirrors and a reconstruction algorithm applied to the recorded voltages from each channel. The reconstructed spectra are very low resolution with features consistent with the instrument response and are not necessarily consistent with the spectral emission features from the plasma. Errors may exist between the reconstructed spectra and the actual emission features due to assumptions in the algorithm. Recently, a high resolution convex crystal spectrometer, VIRGIL, has been installed at NIF with the same line of sight as the Dante. Spectra from L-shell Ag and Xe have been recorded by both VIRGIL and Dante. Comparisons of these two spectroscopic measurements yield insights into the accuracy of the Dante reconstructions.

T Cell Receptor-induced Nuclear Factor κB (NF-κB) Signaling and Transcriptional Activation Are Regulated by STIM1- and Orai1-mediated Calcium Entry

T cell activation following antigen binding to the T cell receptor (TCR) involves the mobilization of intracellular Ca(2+) to activate the key transcription factors nuclear factor of activated T lymphocytes (NFAT) and NF-κB. The mechanism of NFAT activation by Ca(2+) has been determined. However, the role of Ca(2+) in controlling NF-κB signaling is poorly understood, and the source of Ca(2+) required for NF-κB activation is unknown. We demonstrate that TCR- but not TNF-induced NF-κB signaling upstream of IκB kinase activation absolutely requires the influx of extracellular Ca(2+) via STIM1-dependent Ca(2+) release-activated Ca(2+)/Orai channels. We further show that Ca(2+) influx controls phosphorylation of the NF-κB protein p65 on Ser-536 and that this posttranslational modification controls its nuclear localization and transcriptional activation. Notably, our data reveal that this role for Ca(2+) is entirely separate from its upstream control of IκBα degradation, thereby identifying a novel Ca(2+)-dependent distal step in TCR-induced NF-κB activation. Finally, we demonstrate that this control of distal signaling occurs via Ca(2+)-dependent PKCα-mediated phosphorylation of p65. Thus, we establish the source of Ca(2+) required for TCR-induced NF-κB activation and define a new distal Ca(2+)-dependent checkpoint in TCR-induced NF-κB signaling that has broad implications for the control of immune cell development and T cell functional specificity.

Use of a priori spectral information in the measurement of x-ray flux with filtered diode arrays

Filtered x-ray diode (XRD) arrays are often used to measure x-ray spectra vs. time from spectrally continuous x-ray sources such as hohlraums. A priori models of the incident x-ray spectrum enable a more accurate unfolding of the x-ray flux as compared to the standard technique of modifying a thermal Planckian with spectral peaks or dips at the response energy of each filtered XRD channel. A model x-ray spectrum consisting of a thermal Planckian, a Gaussian at higher energy, and (in some cases) a high energy background provides an excellent fit to XRD-array measurements of x-ray emission from laser heated hohlraums. If high-resolution measurements of part of the x-ray emission spectrum are available, that information can be included in the a priori model. In cases where the x-ray emission spectrum is not Planckian, candidate x-ray spectra can be allowed or excluded by fitting them to measured XRD voltages. Examples are presented from the filtered XRD arrays, named Dante, at the National Ignition Facility and the Laboratory for Laser Energetics.

Epithelial-intrinsic IKKα expression regulates group 3 innate lymphoid cell responses and antibacterial immunity

Innate lymphoid cells (ILCs) are critical for maintaining epithelial barrier integrity at mucosal surfaces; however, the tissue-specific factors that regulate ILC responses remain poorly characterized. Using mice with intestinal epithelial cell (IEC)-specific deletions in either inhibitor of κB kinase (IKK)α or IKKβ, two critical regulators of NFκB activation, we demonstrate that IEC-intrinsic IKKα expression selectively regulates group 3 ILC (ILC3)-dependent antibacterial immunity in the intestine. Although IKKβ(ΔIEC) mice efficiently controlled Citrobacter rodentium infection, IKKα(ΔIEC) mice exhibited severe intestinal inflammation, increased bacterial dissemination to peripheral organs, and increased host mortality. Consistent with weakened innate immunity to C. rodentium, IKKα(ΔIEC) mice displayed impaired IL-22 production by RORγt(+) ILC3s, and therapeutic delivery of rIL-22 or transfer of sort-purified IL-22-competent ILCs from control mice could protect IKKα(ΔIEC) mice from C. rodentium-induced morbidity. Defective ILC3 responses in IKKα(ΔIEC) mice were associated with overproduction of thymic stromal lymphopoietin (TSLP) by IECs, which negatively regulated IL-22 production by ILC3s and impaired innate immunity to C. rodentium. IEC-intrinsic IKKα expression was similarly critical for regulation of intestinal inflammation after chemically induced intestinal damage and colitis. Collectively, these data identify a previously unrecognized role for epithelial cell-intrinsic IKKα expression and TSLP in regulating ILC3 responses required to maintain intestinal barrier immunity.

Understanding high endothelial venules: Lessons for cancer immunology

High endothelial venules (HEVs) are blood vessels especially adapted for lymphocyte trafficking which are normally found in secondary lymphoid organs such as lymph nodes (LN) and Peyer's patches. It has long been known that HEVs develop in non-lymphoid organs during chronic inflammation driven by autoimmunity, infection or allografts. More recently, HEVs have been observed in solid, vascularized tumors and their presence correlated with reduced tumor size and improved patient outcome. It is proposed that newly formed HEV promote antitumor immunity by recruiting naive lymphocytes into the tumor, thus allowing the local generation of cancerous tissue-destroying lymphocytes. Understanding how HEVs develop and function are therefore important to unravel their role in human cancers. In LN, HEVs develop during embryonic and early post-natal life and are actively maintained by the LN microenvironment. Systemic blockade of lymphotoxin-β receptor leads to HEV de-differentiation, but the LN components that induce HEV differentiation have remained elusive. Recent elegant studies using gene-targeted mice have demonstrated clearly that triggering the lymphotoxin-β receptor in endothelial cells (EC) induces the differentiation of HEV and that CD11c⁺ dendritic cells play a crucial role in this process. It will be important to determine whether lymphotoxin-β receptor-dependent signaling in EC drives the development of HEV during tumorigenesis and which cells have HEV-inducer properties. This may reveal therapeutic approaches to promote HEV neogenesis and determine the impact of newly formed HEV on tumor immunity.

Grain-size-independent plastic flow at ultrahigh pressures and strain rates

A basic tenet of material science is that the flow stress of a metal increases as its grain size decreases, an effect described by the Hall-Petch relation. This relation is used extensively in material design to optimize the hardness, durability, survivability, and ductility of structural metals. This Letter reports experimental results in a new regime of high pressures and strain rates that challenge this basic tenet of mechanical metallurgy. We report measurements of the plastic flow of the model body-centered-cubic metal tantalum made under conditions of high pressure (>100  GPa) and strain rate (∼10(7)  s(-1)) achieved by using the Omega laser. Under these unique plastic deformation ("flow") conditions, the effect of grain size is found to be negligible for grain sizes >0.25  μm sizes. A multiscale model of the plastic flow suggests that pressure and strain rate hardening dominate over the grain-size effects. Theoretical estimates, based on grain compatibility and geometrically necessary dislocations, corroborate this conclusion.

NEMO-binding domain peptide inhibition of inflammatory signal-induced NF-κB activation in vivo

NF-κB comprises a family of transcription factors that regulate the expression of diverse gene families essential for inflammatory and immune responses as well as cell survival and cell death pathways. Aberrant NF-κB transcriptional activity plays pivotal roles in a large number of human pathologies, including a variety of cancers and chronic inflammatory diseases. Therefore, there has been a large increase in studies aimed at identifying and testing drugs or small molecule inhibitors that would specifically block NF-κB activation in inflammatory diseases and cancer. In this chapter, we describe an in vivo system to test the inhibitory effects of the NEMO-binding domain (NBD) peptide on NF-κB activation specifically in the vascular endothelium and lymphocytes in mice. We demonstrate that pretreatment of mice with the NBD peptide reduces the NF-κB induced gene expression of cell adhesion molecules and DNA-binding activity following systemic LPS stimulation. These methods can be further used to test alternate inhibitors for effects on NF-κB signaling in murine endothelium and immune cells.

Noncanonical NF-κB activation and SDF-1 expression in human endothelial cells

NF-κB is a family of transcription factors regulated through two distinct signaling cascades, the classical and the Noncanonical NF-κB pathways. Noncanonical NF-κB plays important roles in the immune system, as it is necessary for lymphoid organogenesis and B-cell survival and differentiation, as well as osteoclastogenesis. In the last few years, there has been an increased number of studies focusing on both identifying the upstream events that regulate the noncanonical NF-κB pathway as well as determining the physiological roles of noncanonical NF-κB in normal and disease pathologies, such as cancer and autoimmune diseases. Dysregulation of noncanonical NF-κB has now been associated with the pathogenesis of several types of lymphomas and autoimmune diseases and is believed to contribute to chronic inflammatory diseases, including ulcerative colitis. These studies suggest that targeting the Noncanonical pathway, similar to classical NF-κB, may have some therapeutic potential in the future; however, there is still quite a bit about the regulation of the noncanonical signaling that remains to be defined. In this chapter we describe the use of HUVEC, as an in vitro model for examining noncanonical NF-κB signaling in response to different stimuli. We demonstrate two different methods to measure noncanonical NF-κB activation: the processing of p100 to p52, and noncanonical NF-κB-dependent gene expression of CXCL12. The first method examines a key regulatory requirement for noncanonical NF-κB activation, by which p100 undergoes proteolytic cleavage to relieve the inhibition of NF-κB dimers for nuclear translocation and activation of gene transcription. The latter demonstrates the downstream effects of activated noncanonical NF-κB in response to stimuli.

Stable reconstitution of IKK-deficient mouse embryonic fibroblasts

Retroviral transduction is an invaluable technique in molecular biology used to express proteins encoded by nonviral genes in mammalian cells. A key feature of this technique is the ability to create cell lines that stably express the protein of interest and can be cultured long term. Here we describe a retroviral transduction procedure for mouse embryonic fibroblasts (MEFs) that uses Platinum-E cells to rapidly package high-titer, helper-free retrovirus. This technique is useful to study the role of key signaling kinases in the NF-κB signal transduction pathway.

Gamma ray measurements with photoconductive detectors using a dense plasma focus

Photons in the MeV range emitted from the dense plasma focus (DPF) at the NSTec North Las Vegas Facility have been measured with both neutron-damaged GaAs and natural diamond photoconductive detectors (PCDs). The DPF creates or "pinches" plasmas of various gases (e.g., H2, D2, Ne, Ar., etc.) that have enough energy to create MeV photons from either bremsstrahlung and/or (n,n(')) reactions if D2 gas is used. The high bandwidth of the PCDs enabled the first ever measurement of the fast micro-pinches present in DPF plasmas. Comparisons between a slower more conventional scintillator/photomultiplier tube based nuclear physics detectors were made to validate the response of the PCDs to fast intense MeV photon signals. Significant discrepancies in the diamond PCD responses were evident.

A geophysical shock and air blast simulator at the National Ignition Facility

The energy partitioning energy coupling experiments at the National Ignition Facility (NIF) have been designed to measure simultaneously the coupling of energy from a laser-driven target into both ground shock and air blast overpressure to nearby media. The source target for the experiment is positioned at a known height above the ground-surface simulant and is heated by four beams from the NIF. The resulting target energy density and specific energy are equal to those of a low-yield nuclear device. The ground-shock stress waves and atmospheric overpressure waveforms that result in our test system are hydrodynamically scaled analogs of full-scale seismic and air blast phenomena. This report summarizes the development of the platform, the simulations, and calculations that underpin the physics measurements that are being made, and finally the data that were measured. Agreement between the data and simulation of the order of a factor of two to three is seen for air blast quantities such as peak overpressure. Historical underground test data for seismic phenomena measured sensor displacements; we measure the stresses generated in our ground-surrogate medium. We find factors-of-a-few agreement between our measured peak stresses and predictions with modern geophysical computer codes.

Negative feedback regulation of NF-κB-inducing kinase is proteasome-dependent but does not require cellular inhibitors of apoptosis

Non-canonical NF-κB signaling is controlled by the precise regulation of NF-κB inducing kinase (NIK) stability. NIK is constitutively ubiquitylated by cellular inhibitor of apoptosis (cIAP) proteins 1 and 2, leading to its complete proteasomal degradation in resting cells. Following stimulation, cIAP-mediated ubiquitylation of NIK ceases and NIK is stabilized, allowing for inhibitor of κB kinase (IKK)α activation and non-canonical NF-κB signaling. Non-canonical NF-κB signaling is terminated by feedback phosphorylation of NIK by IKKα that promotes NIK degradation; however, the mechanism of active NIK protein turnover remains unknown. To address this question, we established a strategy to precisely distinguish between basal degradation of newly synthesized endogenous NIK and induced active NIK in stimulated cells. Using this approach, we found that IKKα-mediated degradation of signal-induced activated NIK occurs through the proteasome. To determine whether cIAP1 or cIAP2 play a role in active NIK turnover, we utilized a Smac mimetic (GT13072), which promotes degradation of these E3 ubiquitin ligases. As expected, GT13072 stabilized NIK in resting cells. However, loss of the cIAPs did not inhibit proteasome-dependent turnover of signal-induced NIK showing that unlike the basal regulatory mechanism, active NIK turnover is independent of cIAP1 and cIAP2. Our results therefore establish that the negative feedback control of IKKα-mediated NIK turnover occurs via a novel proteasome-dependent and cIAP-independent mechanism.

A phase I clinical trial of systemically delivered NEMO binding domain peptide in dogs with spontaneous activated B-cell like diffuse large B-cell lymphoma

Activated B-Cell (ABC) Diffuse Large B-Cell Lymphoma (DLBCL) is a common, aggressive and poorly chemoresponsive subtype of DLBCL, characterized by constitutive canonical NF-κB signaling. Inhibition of NF-κB signaling leads to apoptosis of ABC-DLBCL cell lines, suggesting targeted disruption of this pathway may have therapeutic relevance. The selective IKK inhibitor, NEMO Binding Domain (NBD) peptide effectively blocks constitutive NF-κB activity and induces apoptosis in ABC-DLBCL cells in vitro. Here we used a comparative approach to determine the safety and efficacy of systemic NBD peptide to inhibit constitutive NF-κB signaling in privately owned dogs with spontaneous newly diagnosed or relapsed ABC-like DLBCL. Malignant lymph nodes biopsies were taken before and twenty-four hours after peptide administration to determine biological effects. Intravenous administration of <2 mg/kg NBD peptide was safe and inhibited constitutive canonical NF-κB activity in 6/10 dogs. Reductions in mitotic index and Cyclin D expression also occurred in a subset of dogs 24 hours post peptide and in 3 dogs marked, therapeutically beneficial histopathological changes were identified. Mild, grade 1 toxicities were noted in 3 dogs at the time of peptide administration and one dog developed transient subclinical hepatopathy. Long term toxicities were not identified. Pharmacokinetic data suggested rapid uptake of peptide into tissues. No significant hematological or biochemical toxicities were identified. Overall the results from this phase I study indicate that systemic administration of NBD peptide is safe and effectively blocks constitutive NF-κB signaling and reduces malignant B cell proliferation in a subset of dogs with ABC-like DLBCL. These results have potential translational relevance for human ABC-DLBCL.

Noncanonical NF-κB signaling is limited by classical NF-κB activity

Precise regulation of nuclear factor κB (NF-κB) signaling is crucial for normal immune responses, and defective NF-κB activity underlies a range of immunodeficiencies. NF-κB is activated through two signaling cascades: the classical and noncanonical pathways. The classical pathway requires inhibitor of κB kinase β (IKKβ) and NF-κB essential modulator (NEMO), and hypomorphic mutations in the gene encoding NEMO (ikbkg) lead to inherited immunodeficiencies, collectively termed NEMO-ID. Noncanonical NF-κB activation requires NF-κB-inducing kinase (NIK) and IKKα, but not NEMO. We found that noncanonical NF-κB was basally active in peripheral blood mononuclear cells from NEMO-ID patients and that noncanonical NF-κB signaling was similarly enhanced in cell lines lacking functional NEMO. NIK, which normally undergoes constitutive degradation, was aberrantly present in resting NEMO-deficient cells, and regulation of its abundance was rescued by reconstitution with full-length NEMO, but not a mutant NEMO protein unable to physically associate with IKKα or IKKβ. Binding of NEMO to IKKα was not required for ligand-dependent stabilization of NIK or noncanonical NF-κB signaling. Rather, an intact and functional IKK complex was essential to suppress basal NIK activity in unstimulated cells. Despite interacting with IKKα and IKKβ to form an IKK complex, NEMO mutants associated with immunodeficiency failed to rescue classical NF-κB signaling or reverse the accumulation of NIK. Together, these findings identify a crucial role for classical NF-κB activity in the suppression of basal noncanonical NF-κB signaling.

Triggering ubiquitination of IFNAR1 protects tissues from inflammatory injury

Type 1 interferons (IFN) protect the host against viruses by engaging a cognate receptor (consisting of IFNAR1/IFNAR2 chains) and inducing downstream signaling and gene expression. However, inflammatory stimuli can trigger IFNAR1 ubiquitination and downregulation thereby attenuating IFN effects in vitro. The significance of this paradoxical regulation is unknown. Presented here results demonstrate that inability to stimulate IFNAR1 ubiquitination in the Ifnar1(SA) knock-in mice renders them highly susceptible to numerous inflammatory syndromes including acute and chronic pancreatitis, and autoimmune and toxic hepatitis. Ifnar1(SA) mice (or their bone marrow-receiving wild type animals) display persistent immune infiltration of inflamed tissues, extensive damage and gravely inadequate tissue regeneration. Pharmacologic stimulation of IFNAR1 ubiquitination is protective against from toxic hepatitis and fulminant generalized inflammation in wild type but not Ifnar1(SA) mice. These results suggest that endogenous mechanisms that trigger IFNAR1 ubiquitination for limiting the inflammation-induced tissue damage can be purposely mimicked for therapeutic benefits.

Demonstration of a 13-keV Kr K-shell x-ray source at the National Ignition Facility

We report 3% conversion efficiency of laser energy into Kr K-shell (≈13 keV) radiation, consistent with theoretical predictions. This is ≈10× greater than previous work. The emission was produced from a 4.1-mm-diameter, 4-mm-tall gas pipe target filled with 1.2 or 1.5 atm of Kr gas. 160 of the National Ignition Facility laser beams deposited ≈700 kJ of 3ω light into the target in an ≈140 TW, 5.0-ns-duration square pulse. The Dante diagnostics measured ≈5 TW into 4π solid angle of ≥12 keV x rays for ≈4 ns, which includes both continuum emission and flux in the Kr He_{α} line at 13 keV.

Time-resolved soft x-ray spectra from laser-produced Cu plasma

The volumetric heating of a thin copper target has been studied with time resolved x-ray spectroscopy. The copper target was heated by a plasma produced using the Lawrence Livermore National Laboratory's Compact Multipulse Terawatt (COMET) laser. A variable spaced grating spectrometer coupled to an x-ray streak camera measured soft x-ray emission (800-1550 eV) from the back of the copper target to characterize the bulk heating of the target. Radiation hydrodynamic simulations were modeled in two-dimensions using the HYDRA code. The target conditions calculated by HYDRA were post-processed with the atomic kinetics code CRETIN to generate synthetic emission spectra. A comparison between the experimental and simulated spectra indicates the presence of specific ionization states of copper and the corresponding electron temperatures and ion densities throughout the laser-heated copper target.

Source geometric considerations for OMEGA Dante measurements

The Dante is a 15 channel filtered diode array which is installed on the OMEGA laser facility at the Laboratory for Laser Energetics, University of Rochester. The system yields the spectrally and temporally resolved radiation flux from 50 eV to 10 keV from various targets (i.e., Hohlraum, gas pipes, etc.). The absolute flux is determined from the radiometric calibration of the x-ray diodes, filters, and mirrors and an unfold algorithm applied to the recorded voltages from each channel. The unfold algorithm assumes an emitting source that is spatially uniform and has a constant area as a function of photon energy. The emitting x-ray source is usually considered to be the laser entrance hole (LEH) of a given diameter for Hohlraum type targets or the effective wall area of high conversion efficiency K-shell type targets. This assumption can be problematic for several reasons. High intensity regions or "hot spots" in the x-ray are observed where the drive laser beams strike the target. The "hot spots" create non-uniform emission seen by the Dante. Additionally, thinned walled (50 μm) low-Z targets (C(22)H(10)N(2)O(5)) have an energy dependent source size since the target's walls will be fully opaque for low energies (E < 2-3 keV) yet fully transmissive at higher energies. Determining accurate yields can be challenging for these types of targets. Discussion and some analysis will be presented.

A critical role for SOCS3 in innate resistance to Toxoplasma gondii

The innate and adaptive immune responses that confer resistance to the intracellular pathogen Toxoplasma gondii critically depend on IL-12 production, which drives interferon-γ (IFN-γ) expression. Certain cytokines can activate STAT3 and limit IL-12 production to prevent infection-associated immune pathology, but T. gondii also directly activates STAT3 to evade host immunity. We show that suppressor of cytokine signaling molecule 3 (SOCS3), a target of STAT3 that limits signaling by the pleiotropic cytokine IL-6, is upregulated in response to infection but is dispensable for the immune-inhibitory effects of T. gondii. Unexpectedly, mice with targeted deletion of SOCS3 in macrophages and neutrophils have reduced IL-12 responses and succumb to toxoplasmosis. Anti-IL-6 administration or IL-12 treatment blocked disease susceptibility, suggesting that in the absence of SOCS3, macrophages are hypersensitive to the anti-inflammatory properties of IL-6. Thus, SOCS3 has a critical role in suppressing IL-6 signals and promoting immune responses to control T. gondii infection.

Gold charge state distributions in highly ionized, low-density beam plasmas

We present a systematic study of Au charge state distributions (CSDs) from low density, nonlocal thermodynamic equilibrium plasmas created in the Livermore electron beam ion traps (EBIT-I and EBIT-II). X-ray emission from Ni-like to Kr-like Au ions has been recorded from monoenergetic electron beam plasmas having E(beam)=2.66, 2.92, 3.53, and 4.54 keV, and the CSDs of the beam plasmas have been inferred by fitting the collisionally excited line transitions and radiative recombination emission features with synthetic spectra. We have modeled the beam plasmas using a collisional-radiative code with various treatments of the atomic structure for the complex M- and N-shell ions and find that only models with extensive doubly excited states can properly account for the dielectronic recombination (DR) channels that control the CSDs. This finding would be unremarkable for plasmas with thermal electron distributions, where many such states are sampled, and the importance of DR is well established. But in an EBIT source, the beam is resonant with only a subset of such states having spectator electrons in orbitals with high principal quantum number n (8≤n≤20). The inclusion of such states in the model was also necessary to obtain agreement with observed stabilizing transitions in the x-ray spectra.

NEMO-binding domain peptide inhibits constitutive NF-κB activity and reduces tumor burden in a canine model of relapsed, refractory diffuse large B-cell lymphoma

PURPOSE

Activated B-cell diffuse large B-cell lymphoma (ABC-DLBCL) is an aggressive, poorly chemoresponsive lymphoid malignancy characterized by constitutive canonical NF-κB activity that promotes lymphomagenesis and chemotherapy resistance via overexpression of antiapoptotic NF-κB target genes. Inhibition of the canonical NF-κB pathway may therefore have therapeutic relevance in ABC-DLBCL. Here, we set out to determine whether dogs with spontaneous DLBCL have comparative aberrant constitutive NF-κB activity and to determine the therapeutic relevance of NF-κB inhibition in dogs with relapsed, resistant DLBCL.

EXPERIMENTAL DESIGN

Canonical NF-κB activity was evaluated by electrophoretic mobility shift assays and immunoblot analyses, and NF-κB target gene expression was measured by quantitative real time PCR. Primary malignant canine B lymphocytes were treated with the selective IKK complex inhibitor NF-κB essential modulator-binding domain (NBD) peptide and evaluated for NF-κB activity and apoptosis. NBD peptide was administered intranodally to dogs with relapsed B-cell lymphoma and NF-κB target gene expression and tumor burden were evaluated pre- and post-treatment.

RESULTS

Constitutive canonical NF-κB activity and increased NF-κB target gene expression were detected in primary DLBCL tissue. NBD peptide inhibited this activity and induced apoptosis of primary malignant B cells in vitro. Intratumoral injections of NBD peptide to dogs with relapsed DLBCL inhibited NF-κB target gene expression and reduced tumor burden.

CONCLUSIONS

This work shows that dogs with spontaneous DLBCL represent a clinically relevant, spontaneous, large animal model for human ABC-DLBCL and shows the therapeutic relevance of NF-κB inhibition in the treatment of ABC-DLBCL. These results have important translational relevance for ABC-DLBCL treatment in human patients.

The RET/PTC3 oncogene activates classical NF-κB by stabilizing NIK

The oncogenic fusion protein RET/PTC3 (RP3) that is expressed in papillary thyroid carcinoma (PTC) and thyroid epithelia in Hashimoto's thyroiditis activates nuclear factor-kappa B (NF-κB) and induces pro-inflammatory gene expression; however, the mechanism of this activation is unknown. To address this, we expressed RP3 in murine embryonic fibroblasts (MEFs) lacking key classical and noncanonical NF-κB signaling components. In wild-type MEFs, RP3 upregulated CCL2, CXCL1, granulocyte-macrophage colony-stimulating factor and tumor necrosis factor expression and activated classical but not noncanonical NF-κB. RP3-activated NF-κB in IκB kinase (IKK)β(-/-) MEFs but not IKKα- or NF-κB essential modulator (NEMO)-deficient cells and activation was inhibited by a peptide that blocks NEMO binding to the IKKs. RP3 increased the levels of NF-κB-inducing kinase (NIK) and did not activate NF-κB in NIK-deficient MEFs. Notably, NIK stabilization was not accompanied by TRAF3 degradation demonstrating that RP3 disrupts normal basal NIK regulation. Dominant-negative NIK blocked RP3-induced NF-κB activation and an RP3 signaling mutant (RP3(Y588F)) did not stabilize NIK. Finally, examination of PTC specimens revealed strong positive staining for NIK. We therefore conclude that RP3 activates classical NF-κB via NIK, NEMO and IKKα. Importantly, our findings reveal a novel mechanism for oncogene-induced NF-κB activation via stabilization of NIK.

Classical NF-kappaB activation negatively regulates noncanonical NF-kappaB-dependent CXCL12 expression

Ligation of the lymphotoxin-β receptor (LTβR) by LIGHT (lymphotoxin-related inducible ligand that competes for glycoprotein D binding to herpes virus entry mediator on T cells (TNFSF14)) activates the noncanonical (NC) NF-κB (nuclear factor-κB) pathway and up-regulates CXCL12 gene expression by human umbilical vein endothelial cells (HUVEC). In contrast, TNF only activates classical NF-κB signaling and does not up-regulate CXCL12. To determine whether cross-talk between the classical and NC pathways affects CXCL12 expression, we investigated the effects of TNF on LIGHT signaling in HUVEC. We show here that TNF inhibits both basal and LIGHT-induced CXCL12 expression. Negative regulation by TNF requires the classical NF-κB pathway as inhibition of basal and induced CXCL12 was reversed in HUVEC-expressing dominant negative IκB (inhibitor of NF-κB) kinase (IKK)β (IKKβ(K44M)). TNF did not inhibit the NC NF-κB pathway activation as LIGHT-induced p100 processing to p52 was intact; however, TNF either alone or together with LIGHT up-regulated p100 and RelB expression and induced the nuclear localization of p100-RelB complexes. Enhanced p100 and RelB expression was inhibited by IKKβ(K44M), which led us to question whether the IκB function of elevated p100 mediates the inhibition of CXCL12 expression by TNF. We retrovirally transduced HUVEC to express p100 at a level similar to that up-regulated by TNF; however, basal and LIGHT-induced CXCL12 expression was normal in the transduced cells. In contrast, ectopic RelB expression recapitulated the effects of TNF on NC signaling and inhibited basal and LIGHT-induced CXCL12 expression by HUVEC. Our findings therefore demonstrate that TNF-induced classical NF-κB signaling up-regulates RelB expression that inhibits both basal and NC NF-κB-dependent CXCL12 expression.

Development of a time-resolved soft x-ray spectrometer for laser produced plasma experiments

A 2400 lines/mm variable-spaced grating spectrometer has been used to measure soft x-ray emission (8-22 Å) from laser-produced plasma experiments at Lawrence Livermore National Laboratory's Compact Multipulse Terrawatt (COMET) Laser Facility. The spectrometer was coupled to a Kentech x-ray streak camera to study the temporal evolution of soft x rays emitted from the back of the Mylar and the copper foils irradiated at 10(15) W/cm(2). The instrument demonstrated a resolving power of ∼120 at 19 Å with a time resolution of 31 ps. The time-resolved copper emission spectrum was consistent with a photodiode monitoring the laser temporal pulse shape and indicated that the soft x-ray emission follows the laser heating of the target. The time and spectral resolutions of this diagnostic make it useful for studies of high temperature plasmas.

Calibration of a flat field soft x-ray grating spectrometer for laser produced plasmas

We have calibrated the x-ray response of a variable line spaced grating spectrometer, known as the VSG, at the Fusion and Astrophysics Data and Diagnostic Calibration Facility at the Lawrence Livermore National Laboratory (LLNL). The VSG has been developed to diagnose laser produced plasmas, such as those created at the Jupiter Laser Facility and the National Ignition Facility at LLNL and at both the Omega and Omega EP lasers at the University of Rochester's Laboratory for Laser Energetics. The bandwidth of the VSG spans the range of ∼6-60 Å. The calibration results presented here include the VSG's dispersion and quantum efficiency. The dispersion is determined by measuring the x rays emitted from the hydrogenlike and heliumlike ions of carbon, nitrogen, oxygen, neon, and aluminum. The quantum efficiency is calibrated to an accuracy of 30% or better by normalizing the x-ray intensities recorded by the VSG to those simultaneously recorded by an x-ray microcalorimeter spectrometer.

Uncertainty analysis technique for OMEGA Dante measurements

The Dante is an 18 channel x-ray filtered diode array which records the spectrally and temporally resolved radiation flux from various targets (e.g., hohlraums, etc.) at x-ray energies between 50 eV and 10 keV. It is a main diagnostic installed on the OMEGA laser facility at the Laboratory for Laser Energetics, University of Rochester. The absolute flux is determined from the photometric calibration of the x-ray diodes, filters and mirrors, and an unfold algorithm. Understanding the errors on this absolute measurement is critical for understanding hohlraum energetic physics. We present a new method for quantifying the uncertainties on the determined flux using a Monte Carlo parameter variation technique. This technique combines the uncertainties in both the unfold algorithm and the error from the absolute calibration of each channel into a one sigma Gaussian error function. One thousand test voltage sets are created using these error functions and processed by the unfold algorithm to produce individual spectra and fluxes. Statistical methods are applied to the resultant set of fluxes to estimate error bars on the measurements.

Cutting edge: association with I kappa B kinase beta regulates the subcellular localization of Homer3

The signaling and adaptor protein Homer3 plays a role in controlling immune homeostasis and self-reactivity. Homer3 is recruited to the immune synapse (IS) following TCR ligation, although the mechanisms regulating this subcellular localization are unknown. We show that Homer3 specifically associates with a novel ubiquitin-like domain in the IkappaB kinase (IKK) beta subunit of the IKK complex. Homer3 associates with IKKbeta in T cells and colocalizes with the IKK complex at the IS. However, Homer3 is not required for IKK activation, as NF-kappaB signaling is intact in Homer3-deficient T cells. Instead, the IKK complex recruits Homer3 to the IS following TCR engagement, and we present evidence that this association regulates actin dynamics in T cells. These findings identify a novel interaction between two major signaling proteins and reveal an unexpected NF-kappaB-independent function for the IKK complex in regulating the subcellular localization of Homer3.

A test cassette for x-ray-exposure experiments at the National Ignition Facility

We present the design and operation of a test cassette for exposure of samples to radiation environments at the National Ignition Facility. The cassette provides options for square and round samples and exposure areas; the cassette provides for multiple levels of filtration on a single sample, which allows dynamic range in experiments. The samples had normal lines of sight to the x-ray source in order to have uniform x-ray illumination. The incident x-radiation onto the samples was determined by the choice of filter thicknesses and materials. The samples were held at precise locations, accurate to within a few hundred microns, in the target chamber in order to have a known fluence incident. In the cassette, the samples were held in place in such a way that a minimal "line contact" allows them to have the maximal mechanical response to the x-ray load. We present postshot images of the debris found on films used for filters, and pre- and postexposure specimens.

Constitutive non-canonical NFkappaB signaling in pancreatic cancer cells

Constitutive classical NFkappaB activation has been implicated in the development of pancreatic cancer, and inhibition of classical NFkappaB signaling sensitizes pancreatic cancer cells to apoptosis. However, the role of the more recently described non-canonical NFkappaB pathway has not been specifically addressed in pancreatic cancer. The non-canonical pathway requires stabilization of NIK and IKKalpha-dependent phosphorylation and processing of NFkappaB2/p100 to p52. This leads to the activation of p52-RelB heterodimers that regulate genes encoding lymphoid-specific chemokines and cytokines. We performed qRT-PCR to detect gene expression in a panel of pancreatic ductal adenocarcinoma cell lines (BxPC-3, PCA-2, PANC-1, Capan-1, Hs-766T, AsPC-1, MiaPACA-2) and found only modest elevation of classical NFkappaB-dependent genes. In contrast, each of the tumor cell lines displayed dramatically elevated levels of subsets of the non-canonical NFkappaB target genes CCL19, CCL21, CXCL12, CXCL13 and BAFF. Consistent with activation of the non-canonical pathway, p52 and RelB co-localized in adenocarcinoma cells in sections of pancreatic tumor tissue, and each of the tumor cell lines displayed elevated p52 levels. Furthermore, p52 and RelB co-immunoprecipitated from pancreatic cancer cells and immunoblotting revealed that NIK was stabilized and p100 was constitutively phosphorylated in a subset of the cell lines. Finally, stable overexpression of dominant negative IKKalpha significantly inhibited non-canonical target gene expression in BxPC-3 cells. These findings therefore demonstrate that the non-canonical NFkappaB pathway is constitutively active and functional in pancreatic cancer cells.

NEMO-binding domains of both IKKalpha and IKKbeta regulate IkappaB kinase complex assembly and classical NF-kappaB activation

Proinflammatory NF-kappaB activation requires the IkappaB (inhibitor of NF-kappaB) kinase (IKK) complex that contains two catalytic subunits named IKKalpha and IKKbeta and a regulatory subunit named NF-kappaB essential modulator (NEMO). NEMO and IKKbeta are essential for tumor necrosis factor (TNF)-induced NF-kappaB activation, and we recently demonstrated that NEMO and IKKalpha are sufficient for interleukin (IL)-1-induced signaling. IKKalpha and IKKbeta both contain a functional NEMO-binding domain (NBD); however, the role of NEMO association with each kinase in NF-kappaB signaling and IKK complex formation remains unclear. To address this question, we stably reconstituted IKKalpha(-/-) and IKKbeta(-/-) murine embryonic fibroblasts (MEFs) with wild-type (WT) or NBD-deficient (DeltaNBD) versions of IKKalpha and IKKbeta, respectively. TNF-induced classical NF-kappaB activation in IKKbeta(-/-) MEFs was rescued by IKKbeta(WT) but not IKKbeta(DeltaNBD), whereas neither IKKbeta(WT) nor IKKbeta(DeltaNBD) affected IL-1-induced NF-kappaB signaling. As previously described, classical NF-kappaB transcriptional activity was absent in IKKalpha(-/-) cells. Reconstitution with either IKKalpha(WT) or IKKalpha(DeltaNBD) rescued both IL-1 and TNF-induced transcription, demonstrating that NEMO association is not required for IKKalpha-dependent regulation of NF-kappaB-dependent transcription. Stably expressed IKKalpha(WT) or IKKbeta(WT) associated with endogenous IKKs and NEMO in IKKalpha(-/-) or IKKbeta(-/-) MEFs, respectively, resulting in formation of the heterotrimeric IKKalpha-IKKbeta-NEMO complex. In contrast, although the IKKalpha(DeltaNBD) and IKKbeta(DeltaNBD) mutants associated with endogenous IKKs containing an NBD, these dimeric endogenous IKK-IKK(DeltaNBD) complexes did not associate with NEMO. These findings therefore demonstrate that formation of the heterotrimeric IKKalpha-IKKbeta-NEMO holocomplex absolutely requires two intact NEMO-binding domains.

The IkappaB kinase complex: master regulator of NF-kappaB signaling

The Nuclear Factor-kappa B (NF-kappaB) family of transcription factors regulates the expression of a wide range of genes critical for immune and inflammatory responses, cell survival, immune development, and cell proliferation. Dysregulated NF-kappaB activity occurs in a number of chronic inflammatory diseases and certain types of cancers making NF-kappaB signaling an attractive target for the development of anti-inflammatory and anti-cancer drugs. A pivotal regulator of all inducible NF-kappaB signaling pathways is the IkappaB kinase (IKK) complex that consists of two kinases (IKKalpha and IKKbeta) and a regulatory subunit named NF-kappaB essential modulator (NEMO). Genetic analysis of the IKK complex has identified two separate pathways named the classical and non-canonical mechanisms that are dependent on either NEMO and IKKbeta (classical) or IKKalpha alone (non-canonical). To better understand the mechanisms that regulate IKK complex activity and to address the differential functions of IKKalpha and IKKbeta we have molecularly dissected the IKKs. We describe here how these studies have identified a unique inhibitor of pro-inflammatory NF-kappaB signaling, an unforeseen role for IKKalpha in the classical NF-kappaB pathway, and a novel functional domain in IKKbeta that is not present in IKKalpha.

Cell penetrating peptide inhibitors of nuclear factor-kappa B

The nuclear factor kappa B (NF-kappaB) transcription factors are activated by a range of stimuli including pro-inflammatory cytokines. Active NF-kappaB regulates the expression of genes involved in inflammation and cell survival and aberrant NF-kappaB activity plays pathological roles in certain types of cancer and diseases characterized by chronic inflammation. NF-kappaB signaling is an attractive target for the development of novel anti-inflammatory or anti-cancer drugs and we discuss here how the method of peptide transduction has been used to specifically target NF-kappaB. Peptide transduction relies on the ability of certain small cell-penetrating peptides (CPPs) to enter cells, and a panel of CPP-linked inhibitors (CPP-Is) has been developed to directly inhibit NF-kappaB signaling. Remarkably, several of these NF-kappaB-targeting CPP-Is are effective in vivo and therefore offer exciting potential in the clinical setting.

DNA double-strand breaks activate a multi-functional genetic program in developing lymphocytes

DNA double-strand breaks are generated by genotoxic agents and by cellular endonucleases as intermediates of several important physiological processes. The cellular response to genotoxic DNA breaks includes the activation of transcriptional programs known primarily to regulate cell-cycle checkpoints and cell survival. DNA double-strand breaks are generated in all developing lymphocytes during the assembly of antigen receptor genes, a process that is essential for normal lymphocyte development. Here we show that in murine lymphocytes these physiological DNA breaks activate a broad transcriptional program. This program transcends the canonical DNA double-strand break response and includes many genes that regulate diverse cellular processes important for lymphocyte development. Moreover, the expression of several of these genes is regulated similarly in response to genotoxic DNA damage. Thus, physiological DNA double-strand breaks provide cues that can regulate cell-type-specific processes not directly involved in maintaining the integrity of the genome, and genotoxic DNA breaks could disrupt normal cellular functions by corrupting these processes.

Hypomorphic nuclear factor-kappaB essential modulator mutation database and reconstitution system identifies phenotypic and immunologic diversity

BACKGROUND

Human hypomorphic nuclear factor-kappaB essential modulator (NEMO) mutations cause diverse clinical and immunologic phenotypes, but understanding of their scope and mechanistic links to immune function and genotype is incomplete.

OBJECTIVE

We created and analyzed a database of hypomorphic NEMO mutations to determine the spectrum of phenotypes and their associated genotypes and sought to establish a standardized NEMO reconstitution system to obtain mechanistic insights.

METHODS

Phenotypes of 72 individuals with NEMO mutations were compiled. NEMO L153R and C417R were investigated further in a reconstitution system. TNF-alpha or Toll-like receptor (TLR)-5 signals were evaluated for nuclear factor-kappaB activation, programmed cell death, and A20 gene expression.

RESULTS

Thirty-two different mutations were identified; 53% affect the zinc finger domain. Seventy-seven percent were associated with ectodermal dysplasia, 86% with serious pyogenic infection, 39% with mycobacterial infection, 19% with serious viral infection, and 23% with inflammatory diseases. Thirty-six percent of individuals died at a mean age of 6.4 years. CD40, IL-1, TNF-alpha, TLR, and T-cell receptor signals were impaired in 15 of 16 (94%), 6 of 7 (86%), 9 of 11 (82%), 9 of 14 (64%), and 7 of 18 (39%), respectively. Hypomorphism-reconstituted NEMO-deficient cells demonstrated partial restoration of NEMO functions. Although both L153R and C417R impaired TLR and TNF-alpha-induced NF-kappaB activation, L153R also increased TNF-alpha-induced programmed cell death with decreased A20 expression.

CONCLUSION

Distinct NEMO hypomorphs define specific disease and genetic characteristics. A reconstitution system can identify attributes of hypomorphisms independent of an individual's genetic background. Apoptosis susceptibility in L153R reconstituted cells defines a specific phenotype of this mutation that likely contributes to the excessive inflammation with which it is clinically associated.